Originally Posted by
ericcc65
Someday I'm thinking of switching this to bar end shifters for cost and maintainability down the road, but probably only when the STIs fail or when I can't find bar ends that'll handle 10 speed well anymore. Who knows how many years down the road that'll be.
Bar end shifters are believed to be more durable than STIs because they have fewer moving parts (and are almost completely metal). Shimano still sells BS79 10-speed bar-ends (and 8 and 9 speed bar-ends are also still available). I think you'll be able to find them for a long time if you wish.
Originally Posted by
ericcc65
I would like to convert the 7900 to a wider range cassette. (Well, I'd prefer my knee to get better, but failed surgeries and stumped doctors indicate that's not likely). So it sounds like I can grab any Shimano 9 speed mountain derailleur and any 10 speed cassette, mtn or road. I was initially hesitant about needing a road cassette because I thought they only went up to 32T, which is probably what I'd target, but it would be nice to have a 34T or 36T option. I already have compact cranksets on both bikes, so I'll probably be fine with the short cage version (SS). So, in summary, I'll need a new chain, cassette, and derailleur. Thanks again.
I don't think Shimano offered any of their 9-speed MTB RDs in short-cage (SS) versions; I think they only came in mid-cage (GS) and long-cage (SGS) versions, for double and triple cranksets, respectively.
Personally, I really like the 9-speed XT RDs (XT is roughly Ultegra-level in the MTB lineup).
RD-M770 is "normal" cable routing and Rapid Rise (reverse order shifting)
RD-M771 is "normal" cable routing and shift order
RD-M772 has "shadow" cable routing and "normal" shift order
Or, you could get an XTR RD (XTR is roughly Dura-Ace level)
RD-M970 is "normal" cable routing and Rapid Rise (reverse order shifting)
RD-M971 is "normal" cable routing and shift order
RD-M972 has "shadow" cable routing and "normal" shift order
Shadow cable routing means the cable doesn't have a big loop from the cable stop to the RD, because where the cable enters the RD is up on the top and angled forward.
Shadow also has more of the derailleur upper parallelogram underneath the hanger and cassette, so it's more tucked out of the way.
However, Shadow RDs DO NOT have a cable adjustment barrel (because MTB shifters do). If you use a Shadow RD with a road shifter, you should add an adjustment barrel to one of the cable stops, or use an inline adjuster on one of the cable loops.
Originally Posted by
ericcc65
And in doing some research it looks like I have Tiagra 4600 (it has the window with the shift position indicator). So even if I wanted to change that to a 9 speed mtn derailleur, I could?
The Tiagra mid cage (GS) rear derailleur is rated for a 30t max cog, but it sounds like users have success with 11-32t cassettes. For a 34t or larger cog, a MTB derailleur would work better.